8105

• UCREFRP Catalog Number: 8105
• Author: Haines, G. B., D. W. Beyers and T. Modde.
• Title: Estimation of Winter Survival, Movement and Dispersal of Young Colorado Squawfish in the Green River, Utah.
• USFW Year: 1998.
• USFW - Doc Type: Recovery Program Project 36,
• Copyright Material: YES

278

Y.K. CONVERSE ET AL.

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10
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Depth (m)

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Discharge (cms x 1,000)

Figure 6. Overall change in depth, velocity and cover with discharge. All shoreline types are included in each graph

DISCUSSION

Relationships between humpback chub and geomorphology

Because of the strong influence of geology on the Colorado River ecosystem and the endemic nature of
the native fish community, relationships between aquatic habitat and river geomorphology must be
understood to manage in a manner which is sympathetic for the welfare of resident fish populations.
These relationships seem particularly important to the humpback chub because of its apparent strong
evolutionary and ecological ties to geomorphic structure at different life-history stages and different
spatial scales (Valdez and Clemmer, 1982; Valdez and Ryel, 1995). In a different region, Rabeni and
Jacobson (1993) found a similar relationship. They determined that centrarchid distribution in Ozark
streams was influenced by geomorphology on a reach scale and velocity, depth and substrate at a local
scale.
In this study, we showed that reaches and shoreline types differed physically and that subadult
humpback chub presence and abundance in Grand Canyon were related to these geomorphic differences,
particularly among shoreline types. This study also demonstrated that subadult humpback chub were
specifically associated with a high frequency of cover in channel margins. In fact, the pattern of fish
distribution and abundance among shorelines parallels the frequency of cover among shorelines, with
vegetation, talus and debris fan shorelines having more cover and greater fish densities than bedrock,
cobble and sand shorelines.

(eJ 1998 John Wiley & Sons. Ltd.

Re~ul. Rivers: Res. M~mt. 14: 267-284 (1998)